Multicast and broadcast transmission method and apparatus of a CDMA mobile communication network

ABSTRACT

A transmission method and system that receive packet data destined to multiple subscribers served by a base station controller/packet control function (BSC/PCF) with the BSC/PCF, transmit the packet data from the BSC/PCF to a number of base stations, which provide service to the subscribers, using a single communication link between the BCS/PCF and each of the number of base stations, and transmit the packet data from the number of base stations to the subscribers.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a packet data transmissionmethod in a CDMA mobile communication network and, more particularly, toa multicast and broadcast transmission method.

[0003] 2. Background of the Related Art

[0004] Recently, with the remarkable development in mobile communicationtechnology, mobile communication service providers have begun providingsubscribers with improved functions and various kinds of services. Themobile communication service is expanding its service into the servicearea previously provided only by wired communication. In addition,research on faster and more effective methods and techniques is beingconducted with respect to the transmission of service.

[0005] A multicast, one of multi-address calling, denominates acommunication form made between one transmission side and a plurality ofreceiving sides in a network. For example, a multicast communication islike transmitting an e-mail message to all of the addresses stored in anaddress book. Multicasting is mostly used for teleconferencing, such asvideo-conferencing or audio-conferencing, in which one transmissionparty transmits an image or voice to a plurality of selectedreceiving-party sites. In the case of video-on-demand (VOD), a servertransmits an image to a plurality of subscribers' set-top boxes. Themulticast transmission method is currently used for mobile communicationas a method for providing an e-mail receiving service to a subscriber ortransmitting specific contents to a subscriber group. A broadcast is amethod for transmitting the same data to a plurality of unspecifiedterminals. Contrasted with the multicast, a unicast is a communicationform made between one transmitting party and one receiving party.

[0006]FIG. 1 is a drawing conceptually illustrating a multicast or abroadcast transmission in a CDMA mobile communication network, inaccordance with the related art. In the case that an Internet serverintends to transmit packet data to every terminal (or mobile station) ofa mobile communication system network or to a plurality of mobilestations (MSs) of a particular multicast group, an IP datagram istransmitted to an MS by a multicast (or broadcast) method using a commonsignal channel or by a multicast (or broadcast) method through a PPPlink. The base station controller (BSC) and the packet control function(PCF) are independent equipment, but for the sake of explanation, theyare shown as one equipment block in the drawing.

[0007] The multicast (or broadcast) method using a common signal channelis not suitable for transmitting high speed multimedia, due to thechannel's low speed and because the signal channel may be overloaded.

[0008] As for the multicast (or broadcast) method through the PPP link,which uses a similar transmission method and path to the unicasttransmission, a packet data serving node (PDSN) sets an individual linkto every target MS and transmits the multicast data.

[0009] Accordingly, when an arbitrary server multicasts or broadcastsdata to a plurality of MSs on the Internet, since target MSs of themobile communication network individually occupy a radio trafficchannel, the multicasting method differs little from an individual lineconnection at the side of the mobile communication network.

[0010]FIG. 2 is a drawing illustrating a service connection (from an MSview) between radio protocol objects of a CDMA mobile communicationsystem. The functional object of a radio protocol and a serviceinterface includes a physical channel object 10, such as a commonassignment channel (CACH), a common power control channel (CPCCH), apilot channel (PCH), a common control channel (CCCH), a sync channel(SYNC), a fundamental traffic channel (FCH), a supplemental channel(SCH), a dedicated control channel (DCCH), a reverse access channel(R-ACH), a reverse enhanced access channel (R-EACCH), a broadcastcontrol channel (BCCH), and a paging channel (PCH). The functionalobject of the radio protocol and the service interface also includes alogical channel object 20, such as a common signaling channel (csch) fortransmitting a common signal, a dedicated signaling channel (dsch) fortransmitting a control signal with an assigned MS, and a dedicatedtraffic channel (dtch) allocated to an assigned MS, for transmittinguser data.

[0011] The multiplex and QoS sub-layer is positioned between thephysical channel and the logical channel. This sub-layer includes acommon channel multiplex sub-layer 30, which handles the common channel,and a multiplex sub-layer 40, which handles an individual channelassigned to the MS and controls the data multiplexing/demultiplexing ofthe logical channel and the physical channel. The multiplex and QoSsub-layer further controls a transmission quality.

[0012] A signaling radio burst protocol (SRBP) 50 is positioned betweena signaling link access controller (LAC) 60 and the common channelmultiplex sub-layer 30 and controls the processing of the radio framedata of a signaling message.

[0013] A radio link protocol (RLP) 70 controls an individual channeltransmission so that the individual channel transmission of the packetdata is reliable. The signaling LAC 60 controls the transmissionprocess, so that a message of an upper signaling layer can be reliablytransmitted to the other party, and also controls the authentication ofa message.

[0014] The MS and the Base Station Transceiver Subsystem (BTS) transmitto and receive from each other a signal layer message of an upper layerand individual transmission data through a LAC sub-layer, a media accesscontroller (MAC) sub-layer, and the physical layer. That is, thefunction object and the service interface of the radio protocol onlyinclude a forward/backward individual signal channel (f/r-dsch) and aforward/backward common signal channel (f/r-csch) for transmitting an MScontrol signal and a BTS information signal. Additionally, the functionobject and service interface only have a forward/backward individualchannel (f/r-dtch) for individually transmitting data to a particularMS. The BTS necessarily has the physical channel, but the other channelsin the middle process may exist in the BTS or the BSC according to aparticular implementation.

[0015] The related art multicast service has many problems. For example,in the case that the Internet server multicasts (or broadcasts) to theMS of the mobile communication network, since every MS individuallyoccupies the radio traffic channel, radio resources are substantiallywasted. In addition, since a wired resource of a wired BTS-BSC/PCF-PDSNis occupied for every MS receiving the multicast (or broadcast), theoccupancy of a separate radio traffic channel by every MS is veryinefficient for the multicasting/broadcasting transmission, whentransmitting the same message to a plurality of target MSs.

SUMMARY OF THE INVENTION

[0016] An object of the invention is to solve at least the aboveproblems and/or disadvantages and to provide at least the advantagesdescribed hereinafter.

[0017] Another object of the present invention is to provide a multicastand broadcast transmission method, of a CDMA mobile communicationnetwork, that is capable of reducing a load burden at the side of awired resource (BTS-BSC/PCF-PDSN).

[0018] A further object of the invention is to reduce the load burden ofthe wired resource by adding a channel and a radio protocol object formulticast/broadcast (M/B) data to the side of a radio resource (MS-BTS).

[0019] To achieve at least the above objects in whole or in part, thereis provided a multicast and broadcast transmission method of a CDMAmobile communication network. The method includes receiving M/B packetdata of a different network server transmitted from a PDSN, withoutsetting a link between a packet data serving node (PDSN) and targetmobile stations (MS) in a multicast/broadcast transmission (M/B) of amobile communication network; temporarily storing the received M/Bpacket data, performing an error control procedure and transmitting itto a plurality of MSs through an M/B packet data dedicated channel; andreceiving and processing only M/B packet data by only the target MS, byreferring to header information of the M/B packet data received from thebase station side.

[0020] To achieve at least the above objects in whole or in part, thereis provided a transmission method, including receiving packet datadestined to multiple subscribers served by a base stationcontroller/packet control function (BSC/PCF) with the BSC/PCF;transmitting the packet data from the BSC/PCF to a number of basestations, which provide service to the subscribers, using a singlecommunication link between the BCS/PCF and each of the number of basestations; and transmitting the packet data from the number of basestations to the subscribers.

[0021] To achieve at least the above objects in whole or in part, thereis provided a communication method, including receiving a multicast orbroadcast message transmitted with a subscriber through a common channeland determining, with the subscriber, whether the subscriber is anintended recipient of the multicast or broadcast message, based onheader information within the multicast or broadcast message.

[0022] To achieve at least the above objects in whole or in part, thereis provided a communication method, including receiving packet datadestined to multiple subscribers served by a base stationcontroller/packet control function (BSC/PCF) with the BSC/PCF;transmitting the packet data from the BSC/PCF to a number of basestations, which provide service to the subscribers, using a singlecommunication link between the BCS/PCF and each of the number of basestations; communicating the packet data from the number of base stationsto the subscribers; and determining, with each of the subscribers,whether the subscriber is an intended recipient of the packet data,based on header information within the packet data.

[0023] To achieve at least the above objects in whole or in part, thereis provided a communication method, including a packet data serving node(PDSN) that receives a multicast or broadcast message from a remoteserver as packet data; a base station controller/ packet controlfunction (BSC/PCF) means for receiving the packet data, destined tomultiple subscribers associated with the BSC/PCF means, from the PDSNthrough a single communication link; and a number of base stations,which provide service to the subscribers, that receive the packet datafrom the BSC/PCF means through a single communication link between theBCS/PCF means and each of the number of base stations. Each of thenumber of base stations transmits the packet data to the subscriberswithin the base station's coverage area through a common channel. Also,each of the subscribers determines whether the subscriber is an intendedrecipient of the packet data, based on header information within thepacket data, and no link is established between the PDSN and anyspecific one or more of the subscribers.

[0024] Additional advantages, objects, and features of the inventionwill be set forth in part in the description which follows and in partwill become apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objects and advantages of the invention may be realizedand attained as particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The invention will be described in detail with reference to thefollowing drawings in which like reference numerals refer to likeelements wherein:

[0026]FIG. 1 illustrates a multicast/broadcast transmission in a CDMAmobile communication network, in accordance with the related art;

[0027]FIG. 2 illustrates a service connection from a mobile station viewbetween radio protocol objects of a CDMA mobile communication system, inaccordance with the related art;

[0028]FIG. 3 illustrates a multicast transmission in a CDMA mobilecommunication network, in accordance with a preferred embodiment of thepresent invention;

[0029]FIG. 4 illustrates a service connection between radio protocolobjects viewed from a base station transceiver of the CDMA mobilecommunication system, which service connection provides a radio packetmulticasting/broadcasting in accordance with the preferred embodiment ofthe present invention;

[0030]FIG. 5 illustrates a service connection between radio protocolobjects, viewed from a mobile station of the CDMA mobile communicationsystem, which service connection provides radio packetmulticasting/broadcasting in accordance with the preferred embodiment ofthe present invention;

[0031]FIG. 6 illustrates an example of a packet broadcast/multicast dataprotocol architecture, from the view of a base station transceiver/basestation controller, in accordance with the preferred embodiment of thepresent invention;

[0032]FIG. 7 illustrates an example of a multicast/broadcast link accesscontroller header and a multicast/broadcast medium access controllerheader in accordance with the preferred embodiment of the presentinvention; and

[0033]FIG. 8 illustrates a process flow chart of a packet datamulticasting or broadcasting method in accordance with the preferredembodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0034]FIG. 3 is a drawing conceptually illustrating a multicasttransmission in a CDMA mobile communication network, in accordance witha preferred embodiment of the present invention. When the PDSN receivesmulticast data from an Internet server, it transmits the receivedmulticast data through a BSC/PCF to the BTSs. Unlike the related artPDSN, which sets a link individually for every target MS in thetransmission of multicast data, the PDSN of the present inventiontransmits multicast data to each BTS without setting a link with atarget MS, when the PDSN receives the multicast data.

[0035] The BTS transmits the received data to every MS within a servicearea and temporarily stores it in a buffer. The MS checks whether themulticast/broadcast (M/B) data has been transmitted from a multicastgroup to which it belongs and receives only data from its subscribedgroup.

[0036] If some of the M/B data received by the MS causes an error, theMS requests a retransmission of the corresponding data from the BTS.Then, the BTS re-transmits only the corresponding data, among the M/Bdata stored in the buffer.

[0037] In this manner, the channel for the M/B data and the radioprotocol object are added to the radio resource (MS-BTS) side to therebyconsiderably reduce the load burden at the wired resource(BTS-BSC/PCF-PDSN) side.

[0038]FIG. 4 is a drawing illustrating a service connection betweenradio protocol objects, viewed from a BTS of the CDMA mobilecommunication system, which provides a radio packetmulticasting/broadcasting in accordance with the preferred embodiment ofthe present invention. FIG. 5 is a drawing illustrating a serviceconnection between radio protocol objects, viewed from an MS of the CDMAmobile communication system, which provides a radio packetmulticasting/broadcasting in accordance with the preferred embodiment ofthe present invention.

[0039] As shown in FIG. 4, the BTS-side function object for the radiopacket data multicast/broadcast transmission preferably includes a datapacket controller 100 for identifying M/B packet data and general packetdata and setting an internal process routine when packet data isreceived from the PDSN. The BTS-side function object also includes anM/B LAC 110 for receiving the M/B packet data from the data packetcontroller 100 and outputting a cellular data multicasting protocolservice data unit (CDMP SDU), generated by adding a link header to theM/B packet data. Additionally, the BTS-side function object includes aCDMP 120 for receiving the CDMP SDU, segmenting the CDMP SDU into aplurality of data units, and outputting a CDMP protocol data unit (PDU),generated by adding a multicast header to each separated data unit, to aforward common traffic channel (f-ctch) 130. Moreover, the BTS-sidefunction object includes a common channel multiplex sub-layer 140 forsegmenting the CDMP PDU, inputted through the f-ctch 130, into dataunits each with a Mux PDU type 3 size and transmitting an F-CDCH SDU,generated by adding a Mux header and a CRC code to each segmented dataunit, to the MS through a forward common data channel (F-CDCH )150.

[0040] As a logical channel for transmitting common traffic to a forwarddirection, the f-ctch 130 transmits the M/B packet data from the CDMP120 to the common channel multiplex sub-layer 140. The F-CDCH 150 is aphysical channel set for accessing every MS within a subscribed area.

[0041] As shown in FIG. 5, the MS-side function object for a radiopacket data multicast/broadcast preferably includes a common channelmultiplex sub-layer 240 for removing the Mux header and the CRC codefrom the F-CDCH SDU, which is received through the F-CDCH 250. TheMS-side function object also includes a CDMP 220 for extracting onlyCDMP PDUs of the multicast group for which the corresponding MS hassubscribed, among the CDMP PDUs inputted through the f-ctch 230. TheCDMP 220 also removes the multicast header of the CDMP PDUs and outputsa CDMP SDU block indicating that the CDMP PDUs are aligned in goodorder. The MS-side function object also includes an M/B LAC 210 forreceiving the CDMP SDU block, completing the original CDMP SDU blockwithout omission of any data unit, and outputting packet data without alink header, by removing the link header contained in the CDMP SDUblock. Additionally, the MS-side function object includes a data packetcontroller 200 for transmitting the packet data received from the M/BLAC 210 to an upper application layer.

[0042] As a logical channel for transmitting the common traffic to aforward direction, the f-ctch 230 transmits the M/B packet data from thecommon channel multiplex sub-layer 240 to the CDMP 220. The F-CDCH 250is a physical channel set for receiving the M/B packet data, which theBTS has transmitted to a plurality of unspecified MSs.

[0043]FIG. 6 is a drawing illustrating an example of a packetbroadcast/multicast data protocol architecture in accordance with thepreferred embodiment of the present invention. FIG. 7 is a drawingillustrating an example of a multicast/broadcast LAC header and amulticast/broadcast MAC header in accordance with the preferredembodiment of the present invention. FIG. 8 is a flow chart of processof a packet data multicasting or broadcasting method in accordance withthe preferred embodiment of the present invention.

[0044] The construction and transmission operation of each functionobject for a multicast transmission will now be described with referenceto FIGS. 6, 7, and 8. When the PDSN receives multicasting data from theInternet server, the received multicasting data is transmitted to theplurality of BTSs through the BSCs/PCFs. The BTS transmits the receivedmulticasting data to the data packet controller 100 and the data packetcontroller 100 outputs the multicasting data to the M/B LAC 110 (step1).

[0045] Upon receipt of the multicasting data from the controller 100,the M/B LAC 110 adds a link header (LHD) to the received packet data andgenerates CDMP SDU data. And the M/B LAC 110 outputs the generated CDMPSDU data to the CDMP 120 (step 2). The link header preferably includes asequence number of the CDMP SDU and multicast group identifierinformation.

[0046] The M/B LAC 110 stores the transmitted CDMP SDU data in thebuffer for a predetermined time period. The M/B LAC 110 includes 16buffers for storing the CDMP SDU. The predetermined time period is longenough to guarantee the transmission of the 16 frames to the MS and thereception of the NAK.

[0047] When the CDMP 120 receives the CDMP SDU data from the M/B LAC110, it performs a forward error correction (FEC) coding and adds aredundancy to the data unit (step 3). The FEC uses a convolution coding,turbo coding, interleaving, or repetition method.

[0048] The CDMP 120 segments the encoding data into the maximum 16 CDMPPDUs (protocol data units). And then, the CDMP 120 adds the multicastheader to each CDMP PDU and outputs it to the f-ctch 130 (step 4). Themulticast header includes a sequence number and multicast groupidentifier information.

[0049] After receiving the packet through the f-ctch 130, the commonchannel multiplex sub-layer 140 segments the received packet into a sizesuitable for transmission to the F-CDCH 150, generates a single LTU byattaching a MuxPDU type 3 header, of which ‘sr_id’ is set as ‘0’ to eachdata block, and outputs the F-CDCH service data unit (SDU) to the F-CDCH150 (step 5). The F-CDCH is a data unit consisting of 2 LTUs.

[0050] As a channel used when the BTS broadcasts data to every MS, atleast one F-CDCH 150 should exist for every BTS sector in the servicearea of a BTS. The F-CDCH channel information is one channel that the MScan receive all the time through the f-csch of the BTS.

[0051] The M/B packet data outputted from the F-CDCH 150 of the BTS istransmitted to the MSs (step 6). The MSs receive only the data of themulticast group for which the MS itself has subscribed, among thereceived radio packet data.

[0052] In the case that there are more than two F-CDCHs in the MS andthe BTS, the two F-CDCHs may be operated in such a manner that one isoperated as a primary F-CDCH, for transmitting a normalmulticast/broadcast packet, and the other is operated as a secondaryF-CDCH for re-transmitting a transmission error packet.

[0053] The channel structure of the F-CDCHs 150 and 250 may have thesame construction as that of the F-SCH defined by the 3GPP2 C.S0002-Astandard, which is hereby incorporated by reference. A packet in aMuxPDU type 3 form can be transmitted through the channel to the MS.

[0054] The MuxPDU type 3 packet is defined in the C.S0003-A standard,which is hereby incorporated by reference, and may utilize a servicereference identifier (sr_id) which is used to identify themulticast/broadcast packet and the unicast packet.

[0055] The CRC is added to the MuxPDU type 3 packet to constitute onelogical transmission unit (LTU). Two LTUs makes one F-CDCH SDU.

[0056] The packet data transmitted to the physical layer through theF-CDCH 150 undergoes a predetermined process and is broadcast to the MSwithin a service area (step 6). And the radio signal received by the MSis restored to a F-CDCH SDU in the physical layer and outputted to theF-CDCH 250 (step 7).

[0057] The common channel multiplex sub-layer 240 removes the MuxPDU andthe CRC from the F-CDCH SDU, received through the F-CDCH 250, andoutputs the remaining data unit to the f-ctch 230.

[0058] The CDMP 220 checks the multicast group identifier of the CDMPPDU, received through the f-ctch 230, and receives only the CDMP PDU ofthe multicast group for which the corresponding MS has subscribed.

[0059] Then, the CDMP 220 aligns the received CDMP PDU in good order andperforms an FEC decoding to restore the CDMP SDU (step 9). The restoredCDMP SDU is outputted to the M/B LAC 210 (step 10).

[0060] Upon receipt of the CDMP SDU data through the CDMP 220, the M/BLAC 210 checks a sequence number to check whether a packet has beenmissed. If there is no missed packet, the M/B LAC 210 removes the linkheader contained in the CDMP SDU to extract the packet data. Theextracted packet data is transmitted through the data packet controller200 to the upper application service layer (step 11).

[0061] If a packet is missed, the M/B LAC 210 transmits a negativeacknowledgment (NAK) signal, containing the sequence number and themulticast group identifier information of the corresponding packet, to asignaling LAC 260 (step 12). Then, the signaling LAC 260 transmits theNAK signal through a backward common signal channel (r-csch) 270 or anr-dsch 280 to the signaling LAC 160 of the BTS (step 13).

[0062] The signaling LAC 160 of the BTS transmits the received NAKsignal to the LAC 110 (step 14). The M/B LAC 110 checks the sequencenumber and the multicast group identifier information of the packet tobe re-transmitted and re-transmits the corresponding packet stored inthe buffer to the MS. A re-transmission process of the packet isperformed in the same manner described for steps 2˜11.

[0063] With reference to FIG. 5 and the above description of thepreferred embodiment, the substantial position of each function objectand channel may be different depending on how they are implemented,rather than being fixed. That is, the BSC necessarily has the packetcontroller and the BTS necessarily has the physical channel, but theother channels and function objects in the middle process may exist inthe BTS or the BSC according to a specific implementation.

[0064] As so far described, the multicast and broadcast transmissionmethod of the preferred invention has many advantages. For example, byadding a channel and a radio protocol object for M/B data to the radioresource (MS-BTS) side, the load burden to the side of the wiredresource (BTS-BSC/PCF-PDSN) is much reduced.

[0065] In addition, the high-speed packet data multicast/broadcasting isrealized and the radio resource is more effectively used.

[0066] The foregoing embodiments and advantages are merely exemplary andare not to be construed as limiting the present invention. The presentteaching can be readily applied to other types of apparatuses. Thedescription of the present invention is intended to be illustrative, andnot to limit the scope of the claims. Many alternatives, modifications,and variations will be apparent to those skilled in the art. In theclaims, means-plus-function clauses are intended to cover the structuresdescribed herein as performing the recited function and not onlystructural equivalents but also equivalent structures.

What is claimed is:
 1. A method of performing a multicast and broadcasttransmission, comprising: receiving multicast/broadcast (M/B) packetdata of a different network server, transmitted from a packet dataserving node (PDSN), without setting links between the PDSN and targetmobile stations for an M/B transmission within a mobile communicationnetwork; temporarily storing the received M/B packet data, performing anerror control procedure, and transmitting the received M/B packet datato a plurality of mobile stations through an M/B packet data dedicatedchannel; and processing the M/B packet data by only the target mobilestations that are identified by header information of the received M/Bpacket data.
 2. The method of claim 1, further comprising: identifyingthe M/B packet data and general packet data and setting an internalprocess routine by a data packet controller; receiving the M/B packetdata from the data packet controller and outputting a cellular datamulticasting protocol service data unit (CDMP SDU) by adding a linkheader to the M/B packet data; receiving the CDMP SDU, segmenting theCDMP SDU into a plurality of data units, and outputting a CDMP protocoldata unit (PDU) generated by adding a multicast header to each separateddata unit to a forward common traffic channel (f-ctch); and segmentingthe CDMP PDU inputted through the fctch into a prescribed size andtransmitting a forward common data channel (F-CDCH) SDU generated byadding a Mux header and a CRC code to each segmented data unit to theplurality of mobile stations through a forward common data channel(F-CDCH).
 3. The method of claim 2, wherein the link header comprisesidentification information on the M/B packet data and unicast packetdata.
 4. The method of claim 2, wherein the link header comprisesmulticast group identifier information.
 5. The method of claim 2,wherein the link header comprises a sequence number of the received M/Bpacket data.
 6. The method of claim 2, wherein the inputted CDMP SDU issegmented to a maximum of 16 data units.
 7. The method of claim 2,further comprising performing a forward error correction (FEC) coding.8. The method of claim 2, wherein the multicast header comprises asequence number of the received M/B packet data.
 9. The method of claim2, wherein the multicast header comprises multicast group identifierinformation.
 10. The method of claim 2, wherein the CDMP SDUs are storedin a buffer, for a predetermined time period.
 11. The method of claim 2,wherein the F-CDCH SDU includes two local transmission units generatedby adding the Mux header and the CRC code to each of the segmented dataunits.
 12. The method of claim 1, further comprising: removing a Muxheader and a CRC code from a forward common data channel (F-CDCH)service data unit (SDU) received through a F-CDCH; extracting only CDMPprotocol data units (PDUs) of a multicast group to which a correspondingmobile station has subscribed from a plurality of CDMP PDUs inputtedthrough a forward common traffic channel (f-ctch); removing a multicastheader of the extracted CDMP PDUs; generating a CDMP SDU blockindicating that the extracted CDMP PDUs are aligned in good order;receiving the CDMP SDU block and completing an original CDMP SDU blockwithout omission of any data unit; generating the M/B packet datawithout a link header by removing a link header contained in the CDMPSDU block; and transmitting the M/B packet data to an upper applicationlayer.
 13. The method of claim 12, further comprising performing aforward error correction (FEC) decoding by cellular data multicastingprotocol (CDMP).
 14. The method of claim 12, further comprising checkinga sequence number contained in the multicast header to align the M/Bpacket data.
 15. The method of claim 12, further comprising checkingmulticast group identifier information contained in the multicastheader, in order to extract only the CDMP PDUs of the multicast group towhich the corresponding mobile station has been subscribed.
 16. Themethod of claim 12, further comprising transmitting a negativeacknowledgment (NAK) signal to a base station side for a retransmissionof a corresponding packet when an error occurs in packet transmission.17. The method of claim 16, wherein the NAK signal comprises a sequencenumber and a multicast group identifier of the corresponding packet. 18.The method of claim 1, further comprising: transmitting the M/B packetdata from a cellular data multicasting protocol (CDMP) to a commonchannel multiplex sub-layer using a forward common traffic channel(f-ctch) as a logical channel; and accessing multiple mobile stations ofthe plurality of mobile stations within a subscription area using aforward common data channel (F-CDCH) as a physical channel.
 19. Themethod of claim 18, wherein at least one F-CDCH exists for each sectorof a base station.
 20. The method of claim 18, wherein if there are twoF-CDCHs per sector of a base station, a first F-CDCH transmits a normalM/B packet and a second F-CDCH re-transmits a packet previously receivedwith an error.
 21. The method of claim 1, wherein a base station side ofthe mobile communication network comprises a base station transceiversubsystem and a base station controller.
 22. The method of claim 1,wherein each of the target mobile stations requests re-transmission of apacket from a base station side if there is an error in the received M/Bpacket data.
 23. The method of claim 1, further comprising: transmittingthe M/B packet data from a common channel multiplex sub-layer to acellular data multicasting protocol using a forward common trafficchannel (f-ctch) as a logical channel; and receiving the M/B packet datathat has been transmitted to a plurality of unspecified mobile stationsby a base station side using a forward common data channel (F-CDCH) as aphysical channel.
 24. A method of transmitting data in a mobilecommunication system, comprising: receiving packet data destined to aplurality of subscribers served by a base station controller/packetcontrol function (BSC/PCF) with the BSC/PCF; transmitting the packetdata from the BSC/PCF to a plurality of base stations, which provideservice to the plurality of subscribers, using a single communicationlink between the BCS/PCF and each of the plurality of base stations; andtransmitting the packet data from the plurality of base stations todesignated ones of the plurality of subscribers.
 25. The method of claim24, wherein the packet data comprises at least one of a multicast and abroadcast message.
 26. The method of claim 24, wherein the BSC/PCFreceives the packet data from a packet data serving node through asingle communication link.
 27. The method of claim 24, wherein thepacket data is transmitted to the designated subscribers through acommon channel.
 28. The method of claim 24, wherein the BSC/PCF receivesthe packet data from a packet data serving node (PDSN) and no link isestablished between the PDSN and any specific one of the plurality ofsubscribers.
 29. A method of performing data communication, comprising:receiving at least one of a multicast and a broadcast message with asubscriber terminal through a common channel; determining whether thesubscriber terminal is an intended recipient of the message based onheader information of the message.
 30. The method of claim 29, furthercomprising: transmitting a negative acknowledgment message with thesubscriber terminal if the subscriber terminal is the intended recipientand the message is received with an error; and disposing of the messageif the subscriber terminal is not the intended recipient, withoutproviding the content of the message to a man-machine interface of thesubscriber terminal.
 31. The method of claim 29, wherein the subscriberterminal does not establish a link, which specifically identifies thesubscriber terminal, with a packet data serving node.
 32. A method ofperforming data communication in a mobile communication system,comprising: receiving packet data destined to a plurality of subscribersserved by a base station controller/packet control function (BSC/PCF)with the BSC/PCF; transmitting the packet data from the BSC/PCF to aplurality of base stations, each of which provides service to thesubscribers, using a single communication link between the BCS/PCF andeach of the plurality of base stations; transmitting the packet datafrom the plurality of base stations to the subscribers; and determiningwhether each of the plurality of the subscribers is an intendedrecipient of the packet data, based on header information of the packetdata.
 33. The method of claim 32, wherein the packet data comprises atleast one of a multicast message and a broadcast message.
 34. The methodof claim 32, wherein the BSC/PCF receives the packet data from a packetdata serving node through a single communication link.
 35. The method ofclaim 32, wherein the packet data is transmitted to each of theplurality of subscribers through a common channel.
 36. The method ofclaim 32, wherein the BSC/PCF receives the packet data from a packetdata serving node (PDSN) and wherein no link is established between thePDSN and any specific one of the plurality of subscribers.
 37. Thecommunication method of claim 32, further comprising: transmitting anegative acknowledgment message with each of the plurality ofsubscribers that is determined to be the intended recipient and if thepacket data is received with an error; and disposing of the packet datawith each of the plurality of subscribers that is determined not to bethe intended recipient, without informing a man-machine interface, ofthe respective subscriber, of the packet data content.
 38. Acommunication system, comprising: a packet data serving node (PDSN)configured to receive a multicast or broadcast message from a remoteserver as packet data; a base station controller/packet control function(BSC/PCF) configured to receive the packet data, destined to multiplesubscribers associated with the BSC/PCF, from the PDSN through a singlecommunication link; and a plurality of base stations, each of whichprovides service to the subscribers and each of which is configured toreceive the packet data from the BSC/PCF through a single communicationlink between the BCS/PCF and each of the plurality of base stations,wherein each of the plurality of base stations transmits the packet datato subscribers within a coverage area of the base station through acommon channel, wherein each of the subscribers determines whether thesubscriber is an intended recipient of the packet data, based on headerinformation within the packet data, and wherein no link is establishedbetween the PDSN and any specific one or more of the subscribers.
 39. Abase station of a mobile communication network, comprising: a datapacket controller that identifies multicast/broadcast (M/B) packet dataand general packet data and sets an internal process routine; an M/Blink access controller (LAC) that receives the M/B packet data from thedata packet controller and outputs a cellular data multicasting protocolservice data unit (CDMP SDU), which is generated by adding a link headerto the M/B packet data; a CDMP that receives the CDMP SDU, segments theCDMP SDU into a plurality of data units, and outputs a CDMP protocoldata unit (PDU), generated by adding a multicast header to eachseparated data unit, to a forward common traffic channel (f-ctch); and acommon channel multiplex sub-layer that segments the CDMP PDU inputtedthrough the fctch into a prescribed size and transmits a forward commondata channel (F-CDCH) SDU, generated by adding a Mux header and a CRCcode to each segmented data unit, to the plurality of mobile stationsthrough a forward common data channel (F-CDCH).
 40. A mobile station,comprising: a common channel multiplex sub-layer that removes a Muxheader and a CRC code from a forward common data channel (F-CDCH)service data unit (SDU) received through a F-CDCH; a cellular datamulticasting protocol (CDMP) that extracts only CDMP protocol data units(PDUs) of a multicast group to which the mobile station has subscribed,among the CDMP PDUs inputted through a forward common traffic channel(f-ctch), removes a multicast header of the CDMP PDUs, and outputs aCDMP SDU block indicating that the CDMP PDUs are aligned; an M/B linkaccess controller (LAC) that receives the CDMP SDU block, completes anoriginal CDMP SDU block without omitting a data unit, and outputs theM/B packet data without a link header, by removing the link headercontained in the CDMP SDU block; and a data packet controller thattransmits the M/B packet data received from the M/B LAC to an upperapplication layer.
 41. The method of claim 2, wherein the prescribedsize is a Mux PDU type 3 size.
 42. The method of claim 10, wherein theF-CDCH SDU includes two local transmission units generated by adding theMux header and the CRC code to each of the segmented data units.
 43. Themethod of claim 29, wherein the message is sent from a base stationcontoller/packet control function of a mobile communication system andwherein the subscriber terminal is one of a plurality of mobileterminals.